Three U.S. senators, alarmed by findings of an Associated Press investigation about aging problems at the nation’s nuclear power plants, asked Thursday for a congressional investigation of safety standards and federal oversight at the facilities.

The request by Democrats Barbara Boxer of California and Sheldon Whitehouse of Rhode Island and independent Bernard Sanders of Vermont builds on increased public concern about nuclear safety in recent months — an outcry unlike anything since the Chernobyl nuclear accident in 1986.

Public interest first spiked after the March accident at the Fukushima Dai-ichi nuclear plant in Japan. Concern has been heightened this week as the AP began releasing the results of a yearlong investigation into aging related safety problems at the 104 reactors operating in the United States.

That’s led activists, politicians, critics and safety watchdogs to say they hope to turn the public focus more sharply onto the industry in America and broader regulatory problems at the U.S. Nuclear Regulatory Commission. One after another, they said they hope the result will be tougher relicensing and safety standards, safer storage of spent fuel and better disaster planning.

Janet Tauro, of Brick, N.J., co-founder of Grandmothers, Mothers, and More for Energy Safety who lives near the Oyster Creek nuclear plant, said the latest developments have led her to conclude “the light is really starting to shine on a very closed regulatory agency.”

Senators Boxer, Whitehouse and Sanders asked for the oversight investigation by the Government Accountability Office. Boxer chairs the Senate Committee on Environment and Public Works.

New Jersey’s two Democratic senators, Frank R. Lautenberg and Robert Menendez, made a similar request of the GAO earlier this week.

In recent months, public anxiety over nuclear power has “peaked incredibly,” said engineer Paul Blanch, an industry whistleblower who later returned to work on improving safety. He is now fighting relicensing applications at four sites.

“I was fighting the world, and now I’m only fighting half the world,” Blanch said.

Visits to the website of Fairewinds Associates, a nuclear safety consultant in Burlington, Vt., have exploded from about 80 a day to 7,000 since the Japanese accident, according to chief engineer, Arnie Gundersen. Site visits rose about another 10 percent when the AP series started on Monday.

The AP’s four-part investigative series shows that government and industry have been working in tandem to weaken safety standards to keep aging reactors within the rules. The series also found that there have been leaks of radioactive tritium, often from corroded underground piping, at three-quarters of U.S. commercial nuclear power sites.

In a GAO report released Tuesday by Democratic Reps. Edward J. Markey of Massachusetts and Peter Welch of Vermont, the watchdog agency concluded that nuclear power plant operators haven’t figured out how to quickly find the underground leaks, which often go undetected for years.

The NRC has said it disagrees with AP’s conclusions, but welcomes the attention the stories have generated to nuclear plant safety. The agency defended its standards and approach to safety.

The industry’s Nuclear Energy Institute criticized AP’s overall findings and “selective, misleading reporting” on U.S. nuclear power plant safety.